I have a flat die line image in
jpgformat ready to go to the machine for cutting, but the machine accepts only a red pattern to cut through and the current image has a pattern in blue.
I have tried manually changing the color in Photoshop but there are some curves and edges that I could not color correctly.
How do I change the blue to red in Photoshop? I am using CS6
The machine accepts below red color (though with a white background instead of red):
An easy way to change those line colors to red with Photoshop is to just place a solid red layer on top and set the blending mode to Color.
My concern is that this file is very low quality and has lots of hidden compression artifacts. My ultimate suggestion would be to vectorize the image (can be done in Photoshop but I used Illustrator). It is composed of very simple shapes so vectorization would be trivial.
This would make it easy to quickly change the die lines to whatever color you needed as well as produce a much higher quality output.